A general strategy to enhance upconversion luminescence in rare-earth-ion-doped oxide nanocrystals

Abstract

We report a general strategy to enhance upconversion luminescence from rare-earth-doped oxide nanocrystals through tailoring the local crystal filed around rare earth ions. We show that upconversion luminescence from oxide nanocrystals of various host lattice (Y2O3, Gd2O3 and ZnO) and of diverse rare-earth-ions (such as Er3+, Yb3+/Er3+, Yb3+/Ho3+ and Yb3+/Tm3+) was enhanced by orders of magnitude through an introduction of non-luminescent Li+ ions into the lattice. These oxide nanocrsytals with tailored upconversion luminescence are able to evoke higher photoluminescence from organic dye molecules, posing their potential use in photodynamic therapy of deep tumors.